Prognostic value of myocardial flow reserve obtained by 82-rubidium positron emission tomography in long-term follow-up after heart transplantation

Abstract

Cardiac allograft vasculopathy (CAV) is a leading cause of death following heart transplantation (HTx) and non-invasive prognostic methods in long-term CAV surveillance are needed. We evaluated the prognostic value of myocardial flow reserve (MFR) obtained by 82-rubidium (82Rb) positron emission tomography (PET). Recipients undergoing dynamic rest-stress 82Rb PET between April 2013 and June 2017 were retrospectively evaluated in a single-center study. Evaluation by PET included quantitative myocardial blood flow and semiquantitative myocardial perfusion imaging. Patients were grouped by MFR (MFR ≤\u20092.0 vs MFR >\u20092.0) and the primary outcome was all-cause mortality. A total of 50 patients (68% men, median age 57 [IQR: 43 to 68]) were included. Median time from HTx to PET was 10.0 (6.7 to 16.0) years. In 58% of patients CAV was documented prior to PET. During a median follow-up of 3.6 (2.3 to 4.3) years 12 events occurred. Survival probability by Kaplan–Meier method was significantly higher in the high-MFR group (log-rank P\u2009=\u2009.02). Revascularization (n\u2009=\u20091), new CAV diagnosis (n\u2009=\u20091), and graft failure (n\u2009=\u20094) were more frequent in low-MFR patients. No retransplantation occurred. Myocardial flow reserve appears to offer prognostic value in selected long-term HTx recipients and holds promise as a non-invasive method for CAV surveillance possibly guiding management strategy.